In a renewed effort to limit the spread of COVID-19, the Centers for Disease Control and Prevention is recommending that fully vaccinated Americans wear masks indoors if they’re in an area of substantial or high coronavirus transmission.
The CDC is also recommending universal indoor masking for all teachers, staff, students and visitors inside schools from kindergarten to 12th grade, regardless of vaccination status.
The updated guidance comes as a wave of cases triggered by the highly contagious delta variant sweeps the nation.
For the first time in more than three months, cases are averaging more than 60,000 a day, according to a USA TODAY analysis of Johns Hopkins University data. There are more than 2,000 deaths a week.
“The delta variant is showing every day its willingness to outsmart us and to be an opportunist in areas where we have not shown a fortified response to it,” CDC Director Dr. Rochelle Walensky said in a briefing Tuesday. “COVID-19 continues to present many challenges and has exacted a tremendous toll on our nation.”
CDC recommends masks for vaccinated people: What does high transmissibility mean?
Map of COVID-19 transmission levels by county
Two developments prompted the new CDC recommendation:
- More areas within the U.S. showing high community transmission rates of COVID-19 – in other words, areas with coronavirus infection rates higher than average.
- New science showing fully vaccinated people infected by the delta variant after vaccination can transmit the virus.
Community transmission rates are based on two measurements taken over a rolling seven-day average.
The first is diagnostic based, using nucleic acid amplification tests (NAATs) that show positive results for the virus. NAATs are considered the “gold standard” for detection of COVID-19.
The second is the number of new cases per 100,000 people. If the two indicators suggest different transmission levels, the higher level is selected.
Counties or other areas are separated into four community transmission categories: low, moderate, substantial or high. Here's how they are calculated:
Here's how the ratings break down overall by county:
The delta variant is more contagious than other coronavirus variants:
- It has an incubation period of four days, making it more contagious than the original version, which has a six-day incubation period.
- Those infected with delta infect an average of six people, compared with the four-person infection rate of the original version.
- Delta has caused at least 92% of new infections in the U.S.
Though the delta variant may not be more lethal than the original virus, more people may die because more people are infected.
Learn more: Why more transmissible variants of COVID-19 can be as worrisome as more deadly ones
SOURCE USA TODAY Network reporting and research; Centers for Disease Control and Prevention; Kaiser Health News; Associated Press; nature.com